1. Field of the Invention
The present invention relates to a magnetic recording/reproducing apparatus for recording data on a magnetic recording medium by making use of a recording head or a plurality of recording heads and reproducing signals from a plurality of tracks of the magnetic recording medium by making use of a reproducing head or a plurality of reproducing heads as well as relates to a magnetic recording/reproducing method adopted by the magnetic recording/reproducing apparatus.
2. Description of the Related Art
In recent years, it has been and is being demanded for a magnetic recording/reproducing apparatus to achieve higher density recording in order to increase the capacity of magnetic recording media, and it is demanded to narrow the track width of recording tracks (hereinafter referred to as “narrowing”). To narrowing of tracks, it is a key to improve the accuracy in tracking servo.
For the improvement of tracking servo, a non-tracking method has been proposed and put to practical use as disclosed, for example, in Japanese Patent No. 1,842,057, Japanese Patent No. 1,842,058, Japanese Patent No. 1,842,059, Japanese Patent Laid-open No. Hei 04-370580, and Japanese Patent Laid-open No. Hei 05-020788. In accordance with the non-tracking method, in a magnetic recording/reproducing apparatus, data are recorded separately in blocks for identification on tracks double azimuth recorded by helical scanning so that the data can be re-constructed even if an object track cannot be reproduced by one tracing operation. By the non-tracking system, a margin four times or more of that for position control of a reproducing head within one recording track required in conventional tracking servoing is permitted. In other words, it is permitted to reduce the accuracy in such position control to one fourth or less.
Further, the application of the non-tracking system to a magnetic tape recording/reproducing apparatus is not limited to helical scanning, but the possibility that the non-tracking system may be used in linear recording is studied as disclosed, for example, in Japanese Patent Laid-Open No. Hei 10-283620 or Japanese Patent Laid-Open No. 2003-132504.
However, where a nonmagnetic support member having stretchability such as, for example, a polyester film is used for a substrate of a tape as magnetic recording medium, even if double azimuth recording is performed, the permissible deformation amount is, for example, up to approximately twice the recording track width using tracking servoing together. If a greater amount of deformation occurs, then a signal cannot be reproduced with a sufficiently high S/N ratio. On the other hand, in recording which does not have double azimuths, the width of a guard band which does not extend across tracks must be suppressed to an amount smaller than the deformation amount of the tape in order that the reliability such as the error rate may not be deteriorated even where tracking servoing is used together.
Such problems as described above arise, in signal reproduction systems which have been implemented heretofore, from significant deterioration of the signal quality by reading in of a signal from a plurality of recording tracks at the same time by at least one reproducing head.
This similarly applies also to the non-tracking system. In particular, although a reproducing head apparently reproduces a signal across a plurality of tracks, where timing division is applied, the signal is reproduced normally from one recording track, but reproduction of a plurality of tracks at the same time is not performed.
If an effort to further increase the recording density is taken into consideration, reproduction of a signal from a single recording track at the same time provides a limit to narrowing of tracks.
As a background technique for a magnetic head apparatus, an apparatus is available wherein a plurality of heads are disposed in one block and a plurality of data frames are recorded at a time as a system for the formation in blocks of the same azimuth in order to enhance the recording density. One of such apparatus is disclosed, for example, In Japanese Patent Laid-open No. 2003-338012 or Japanese Patent Laid-open No. 2004-071014.
In the known apparatus, since the reproducing head width must be reduced to approximately one half the width of recording tracks, there is a restriction that a high output of a reproduction signal cannot be obtained. This gives rise to deterioration of the S/N ratio. Therefore, the apparatus are not necessarily suitable for further higher density recording.
In addition, narrowing of tracks provides a limitation at which the azimuth cannot be used any more.